Fluxing and keeping lead from surface oxydation.

[Bird]

I use only beeswax. A lump of it flows across the surface and forms a barrier. Give it a stir every 20 mins, and add a little more.

[BNE]

Fluxing is one of those topics voted MOST LIKELY TO START AN ARGUMENT! This one has been surprisingly nice!

I am in the wax / sawdust camp. I even made sawdust chunks full of wax that I break off into the pot.

Tin Depletion?
I have done XrF tests that show that the amount of Tin you lose to oxidation is not measurable. The test involved leaving a pot on around 800F for a couple of hours. I would scrape the top layer off and XrF at different time intervals. Tin was not depleted in this time period.
Leaving a layer of kitty litter or something else on top of the melt is not helping you keep Tin in the mix.

BNE

[sureYnot]

Thank you, BNE. I had been under the impression that tin oxidized faster than lead. Any insight as to the effect on antimony? Or arsenic?

Sent from my XT1710-02 using Tapatalk

[BNE]

Thank you, BNE. I had been under the impression that tin oxidized faster than lead. Any insight as to the effect on antimony? Or arsenic?

Sent from my XT1710-02 using Tapatalk

Tin does oxidize more quickly than lead, but once that top layer oxidizes, it basically protects the lower layers.

In the test I ran I was not specifically looking for Arsenic, so I can’t answer that one. The percentages of Lead, Tin, and Antimony did not change.

[sureYnot]

Tin does oxidize more quickly than lead, but once that top layer oxidizes, it basically protects the lower layers.

In the test I ran I was not specifically looking for Arsenic, so I can’t answer that one. The percentages of Lead, Tin, and Antimony did not change.

Good stuff. Again, I thank you.

Sent from my XT1710-02 using Tapatalk

[EDG]

In the investment casting industry they often use an argon drip or line to provide a blanket of inert gas on top of the molten metal in the crucible.
For our little pots a stainless steel disk could be floated on top of the lead. This disk will mechanically reduce the surface area of the melt exposed to oxygen.

I once worked at a small shop that had a casting setup to cast silver. The crucible had an airtight cover with an argon purge gas line. There was also a short rubber hose that was a pressure relief exhaust in the cover. In use argon flowed on top of the molten silver. To cast you merely put your thumb over the end of the pressure relief line. The argon built up enough pressure on top of the molten metal and forced it out through a submerged goose neck. The goose neck delivered the silver into a mold mounted on the machine.

[jonp]

I use a potato masher to get the flux to the bottom of the pot

I will now. psst..don't tell my long suffering wife where another of her kitchen gadgets went. I'm still trying to explain the cast iron dutch oven and the blender ( So...you were chopping up aluminum foil for what, exactly???).

[hermans]

Fluxing is one of those topics voted MOST LIKELY TO START AN ARGUMENT! This one has been surprisingly nice!

I am in the wax / sawdust camp. I even made sawdust chunks full of wax that I break off into the pot.

Tin Depletion?
I have done XrF tests that show that the amount of Tin you lose to oxidation is not measurable. The test involved leaving a pot on around 800F for a couple of hours. I would scrape the top layer off and XrF at different time intervals. Tin was not depleted in this time period.
Leaving a layer of kitty litter or something else on top of the melt is not helping you keep Tin in the mix.

BNE

I tend to agree with BNE...not because I could measure the amount of tin lost to oxidation, but just because I can constantly produce perfect boolits from COWW without worrying too much about leaving a protective layer on top of the alloy in the pot.
What I do is stir well with a wooden stick, then add beeswax generously, and try to cast at the lowest possible alloy temperature, controlled with a PID, usually not higher that 695 degrees.
Happy casting